The invention relates to a fuel injection system for mixture compressing, externally ignited internal combustion engines employing continuous fuel injection into the induction tube of the engine. These fuel injection systems employ a measuring element located within the induction tube and, in series therewith, an arbitrarily actuatable butterfly valve. The measuring element moves against a resetting force and causes the displacement of the movable part of a valve disposed within the fuel line for the purpose of metering out a fuel quantity proportional to the air quantity flowing through the induction tube.
Fuel injection systems of this type are designed to automatically provide a favorable fuel-air mixture for all operational conditions of the internal combustion engine so as to make possible a complete combustion of the fuel and hence to avoid, or at least to reduce sharply, the generation of toxic components in the exhaust gas while maintaining the highest possible performance or the least possible fuel consumption of the engine. Accordingly, the fuel quantity must be metered out very precisely to correspond to the requirements of each and every operational state of the internal combustion engine.
In known fuel injection systems of this type, the air quantity flowing through the induction tube is sensed by a measuring element and a quantity of fuel proportional to this air quantity is metered out and is injected by injection nozzles into the induction tube in the vicinity of each engine cylinder. The proportionality existing between the air quantity and the fuel quantity may be altered depending on engine parameters such as rpm, load and temperature.